Study On The Regulation Of Sowing Date On Stem Elongation,Enrichment And Post-anthesis Remobilization Of Winter Wheat

The elongation,enrichment and post-anthesis remobilization of the stem of winter wheat are key factors to the lodging resistance.However,the regulation of stem elongation,dry matter enrichment,dry matter post-anthesis remobilization with different sowing dates and effects of regulation of stem elongation,dry matter enrichment,dry matter post-anthesis remobilization on lodging resistance of winter wheat remains unknown.During the 2015-2016 and 2016-2017 growing seasons,the winter wheat cultivars Tainong(TN18)and Jimai22(JM22)were sown on four dates of October 1,8,15 and 22,represented by D1,D2,D3 and D4 respectively.By studying the effects of sowing date on the duration of elongation process,rate of elongation process,duration of enrichment process,rate of enrichment process,duration of dry matter post-anthesis remobilization process,rate of dry matter postanthesis remobilization process of winter wheat,the regulation effects of stem elongation,dry matter enrichment,dry matter post-anthesis remobilization on lodging resistance of winter wheat and their differences of different sowing dates were clarified.The results show that:1 Effect of sowing date on grain yield of winter wheat Under the conditions of this experiment,the sowing date significantly affected the grain yield and composition of winter wheat.When sowing date was postponed from October 1 to October 22,the number of panicles per unit area of TN18 and JM22 gradually decreased,the number of grains per panicle increased,and the grain weight remained unchanged(2015-2016)or increased(2016-2017),so the yield remained unchanged or increased.2 Effects of sowing date on dry matter accumulation and distribution of various vegetative organs of winter wheatSuitable late sowing(October 22)can reduce the amount of dry matter stored in the vegetative organs storaged before anthesising,the transshipment rate and the contribution rate to the grain.Suitable late sowing can increase the dry matter accumulation of maturity,the dry matter production at jointing-mature stage and proportion of total dry matter,postanthesis photosynthetic production and its contribution to yield,harvest index and lodging resistance of winter wheat.Suitable late sowing got the highest yield.3 Regulation effect of sowing date on elongation,dry matter enrichment and postanthesis remobilization of winter wheatThe duration of elongation and enrichment process of the internode began synchronously,but the duration enrichment process would continue for a certain time after the elongation stops.From grain filling stage to maturity stage,the dry matter of winter wheat internodes gradually decreased due to the remobilization to grain.Suitable late sowing(October 22)shortened the rapid duration elongation process and reduced the maximum length of internode.Moreover,suitable late sowing prolonged the rapid duration of enrichment process and increased the maximum dry matter,postponed the duration of dry matter post-anthesis remobilization.With the delay of sowing date,the length of internode at the anthesis,20 days after anthesis and 30 days after anthesis were decreased,and the dry matter and filling degree at the anthesis,20 days after anthesis and 30 days after anthesis were increased.4 Effect of sowing date on lodging resistance of winter wheatSuitable late sowing(October 22)significantly reduced the length of basal internode of winter wheat,the culm height at the center of gravity of TN18 and JM22 in the middle and late stage of grouting,and increased the diameter,wall thickness,dry weight,filing degree and stem mechanical strength of the second basal internode.The interaction of two factors can improve the lodging resistance index of winter wheat and reduce the risk of lodging after anthesising.The results of correlation analysis and stepwise regression analysis showed that lodging resistance index was negatively correlated with the rapid duration elongation process and rate of the rapid duration elongation process of the second the base internode,positively correlated with the rapid duration of enrichment process,and had no significant correlation with the duration of dry matter post-anthesis remobilization and rate of the post-anthesis remobilization of the second base internode.The results showed that late sowing could shorten the length of base internodes by shortening the duration of rapid elongation,and then reduce the height of center of gravity.Increase the dry matter and filling degree of the second base internodes by increasing rapid duration of enrichment process,and then increase the mechanical strength of base internodes.The interaction between them could increase the lodging resistance index of winter wheat stalks,and then increase the lodging resistance of winter wheat.Dry matter post-anthesis remobilization had little effect on lodging resistance of stem.